One of the most frustrating parts of being a new parent is feeling clueless about your baby's wants and needs. Does a soft, whimpering cry mean he's got a wet diaper—or that he's getting hungry? What about a loud screech? And forget about crying for a moment—what does it mean when your baby rubs her ears, or flails her arms around?

Babies communicate long before they say their first words, says Linda Acredolo, Ph.D., professor emeritus of psychology at University of California, Davis, and author of Baby Signs. "Babies are born with the ability to express several emotions, including distress and contentment," she says. When we read their cues and respond quickly to their needs, she adds, babies feel secure and the parent-child bond is strengthened. Of course, easier said than done—not all babies send the exact same signals, and sometimes it takes months before you feel truly in tune with your baby. Still, some general principles apply. Read on for expert advice on how to decode three major types of baby cues.

Making faces

Little frowns, wrinkled foreheads—your baby's expressions can be fleeting and easy to miss, admits David Hill, M.D., adjunct assistant professor of pediatrics at University of North Carolina Medical School. "Compared to crying, facial expressions are certainly more subtle," he says. Watch closely, however, and you'll soon catch these familiar expressions:

Gaze aversion

A baby who turns his face away from you needs a break from eye contact. "From about two months on, babies disconnect if they're feeling overwhelmed or over stimulated," says Dr. Acredolo. "Sometimes, the baby will turn his head to the side almost stubbornly, or play with his fingers or toes, or even start crying—anything to break contact with an adult."

What to do:

New parents sometimes get overenthusiastic when interacting with baby, says Dr. Acredolo. "These parents will try moving into their baby's line of sight even if the infant has turned away, or they may keep talking, tickling or jostling to win back their baby's attention," she says. Respect your baby's need for down time, and wait patiently and quietly until he turns back to you. "Then, smile broadly and re-engage with your baby," she says.

Smiling

The first true smile usually occurs between six and eight weeks, says Dr. Acredolo. "At this early age, smiles are likely a signal of physical contentment," she says. "My own baby's first smile, for instance, was triggered by the coziness of a warm towel after her bath." But soon, smiles become more controlled, and happen when your baby is around loved ones.

What to do:

Encourage your baby by reacting positively to her first smiles; laugh and smile back at her, tell her how terrific she is—even if she doesn't understand the words, she gets the message.

Copycat

We are blueprints for our babies. "Between three and six months, most infants will learn to imitate facial expressions—fear, surprise, sadness," says Dr. Hill. By nine months, a baby will take in a new situation (i.e. the appearance of a stranger), then look back at her mother's face. "If the baby sees the parent is also distressed, then her anxiety will increase," says Dr. Hill. "Usually, the baby will start clinging or crying."

What to do:

Remember that if you're feeling stressed, your baby will be too. If it's a minor case of anxiety, take some deep, cleansing breaths and consciously relax your facial muscles to ease tension. "In many cases, the act of smiling itself is likely to calm you down," says Dr. Hill. "Follow that with strong, smooth touch such as hugging or patting, to let your baby know everything is okay." (Of course, if you're reaching the point of anger or frustration, you should always hand your baby off to someone else. If you're alone, put him down in a safe place like his crib until you've calmed down.)

Body talk

Studies suggest that about 90 percent of communication by babies and adults is nonverbal, says speech-language pathologist Diane Bahr, author of Nobody Ever Told Me (or my Mother) That! "For instance, many babies make little fists when they're hungry and begin feeding," she says. "Once they are satisfied and full, their hands relax and open." Other common body language cues:

Arching his back

Starting a few weeks after birth, babies begin arching their backs when they're in discomfort, says Michele Saysana, M.D., director of the Pediatric Hospitalist Program at Riley Hospital for Children at the Indiana University School of Medicine. "It might mean he has reflux, especially when the arched back is combined with crying," she says. "The baby will squirm around and move to try to get to a more comfortable position." Often babies arch their backs when they've had enough to eat and want to move away from the breast. (Around 4 or 5 months, this movement might mean something completely different—that your baby is trying to roll over for the first time.)

What to do:

Your baby probably just needs a change of position (after all, she can't move very much herself yet.) If she's in a carrier, car seat or stroller, try taking her out for a few minutes; hold her upright against your shoulder or give her some wiggle time on the floor.

Rubbing eyes and/or ears

Babies will rub their eyes and ears with their hands when they are starting to tire. "Before 6 months, they rub their faces against something if they are tired or itchy," she says. "After that, they might discover an ear by accident, and take comfort in pulling or rubbing it. Ears are a sensitive part of the body, and babies like feeling them."

What to do:

Start your bedtime or naptime routine as soon as baby begins rubbing his ears and face. One caveat: If your baby is rubbing his ears, has a temperature of over 101 degrees and is fussy, he may have an ear infection and you should call your pediatrician, says Dr. Saysana.

Rooting

The rooting reflex is a key to survival, as it helps the baby find food. "A newborn will turn his head whenever something touches his cheek," says Dr. Saysana. "The reflex disappears after the first few weeks, although babies will still turn toward you to nurse—it's not automatic anymore and becomes a cue they are hungry."

What to do:

Use the rooting reflex to your advantage while your baby figures out feeding; a simple touch of the cheek will help him find the breast or bottle.

Startle reflex

Loud noises, bright lights, or a head bobble can trigger the startle reflex—babies jerk, spread out their arms and legs, then quickly pull them back in and cry. The startle reflex is present at birth, but fades between three and six months.

What to do:

Although startling doesn't hurt the baby, it can feel scary and set off a crying fit. To recreate the security of the womb, where sound and light were muffled, try swaddling your baby with a lightweight receiving blanket. (This technique is best for younger babies. By four months, most babies can squirm out of a swaddle, Saysana notes—after six months, swaddling can lead to hip problems.) Click here for instructions on how to swaddle your baby.

Cry baby

Crying is the quickest way for your baby to let you know she's tired, hungry, in painor just plain fussy. But which cry is which? "At birth, all the cries sound pretty much the same," says Bahr. "Newborn babies cry when they inhale and exhale; they don't have much respiratory control." Start listening for variations around one month, explains Bahr—as your baby matures, you'll be able to figure out what she wants from the cry she makes. Here are the biggies:

Hungry cry

A baby will generally wake up hungry and crying for food. "It's a short, low-pitched cry, just over a second in duration," says Bahr. If you don't respond quickly, the cry becomes louder and more intense.

What to do:

Respond to your baby as quickly as possible, especially in the first few months of life. You're not going to spoil your baby by picking him up and feeding him right away. Tending to your baby's hunger immediately teaches him that you'll always be there to care for his needs.

Pain cry

A cry of pain comes on much more suddenly than a hunger cry. It's about twice as long, and continuous- that is, it doesn't rise and fall in pitch.

What to do:

Go through a mental checklist when trying to comfort your baby. Could she have a wet or soiled diaper? Could she be too cold—or too warm? (A baby waking up in a car seat, for instance, is often overheated.) Look your baby over from head to toe. Sometimes a piece of clothing or edge of a diaper is pinching her skin.

Tired cry

Between two and three months, your baby's cries will become more varied, and he may develop a cranky, "tired" cry. "It may be a softer variation of his distress cry, says Bahr. (Don't forget to use common sense in deciphering cries: If your baby's been awake for a couple hours, it's more than likely you're hearing a sleepy cry.)

What to do:

Try rocking in a chair or on your feet, swaying from side to side, gently stroking his head or chest or softly singing. You'll quickly find out what works best to quiet your baby.

Cooing, babbling and laughing

Babies "talk" between two and three months, says Bahr. "They start to match the pitch and variation of the parent's tone." By four to six months, babies experiment even more with their voices; they babble, putting consonant and vowel sounds together and make raspberry sounds. "Her voice can express a range of emotions—happy, mad, irritated, protesting, eager and satisfied," says Bahr.

What to do:

Narrate your activities as you go through the day with your baby ("Now I'm going to run the water for your bath," "Look at the pretty butterfly!") - pausing to let her babble back at you. Encourage her by mimicking the sounds she makes - and enjoy these first, memorable conversations!